[PATCH] dxgi/tests: Remove useless casts to self

[Marvin]

Hi,

While running your changed tests, I think I found new failures.
Being a bot and all I'm not very good at pattern recognition, so I might be
wrong, but could you please double-check?

Full results can be found at:
https://testbot.winehq.org/JobDetails.pl?Key=55342

Your paranoid android.


=== debian10 (32 bit report) ===

dxgi:
dxgi: Timeout

=== debian10 (build log) ===

Task: WineTest did not produce the win32_fr_FR report

=== debian10 (32 bit WoW report) ===

dxgi:
dxgi: Timeout

=== debian10 (build log) ===

Task: WineTest did not produce the wow64 report